PHENYLKETONURIA






Phenylketonuria
is an inherited disease due to faulty metabolism of phenylalanine, characterized by phenylketones in the urine and usually first noted by signs of mental retardation in infancy. Phenylketonuria is better known as PKU, which just shortens the main name. PKU is a genetic disorder that is characterized by an inability of the body to utilize the essential amino acid, phenylalanine. Amino Acids happen to be the building blocks for the bodies proteins. A normal blood phenylalanine level is about 1 mg/dl. In classic PKU, levels may range from 6 to 80mg/dl, but are usually greater than 30mg/dl. Classic PKU is the most common cause of high levels of phenylalanine in the blood.


Inheritance Pattern:
For a child to inherit PKU, both the mother and father must have and pass on the defective gene. This pattern of inheritance is called autosomal recessive. It's possible for a parent to have the defective gene, but not have the disease. This is called being a carrier. Most often, PKU is passed down the family tree by parents who are carriers of the disorder, but don't know it.



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PU Inheritance



Symptoms:
Children that have PKU seem to appear normal at birth. They usually have bue eyes and more fair skin than their other family members. They are trying to prevent this disease in many ways, shapes, and forms including: newborn screening, early identification, and management. Following this will describe what untreated PKU sypmtoms are like:

  • Vomiting
  • Irritability
  • Encazema-type Rash
  • Mousy Odor to Urine

But these are all just the early syptoms. Later symptoms include:
  • Severe brain problems;(mental retardation and seizures)
  • Microcephaly (small head)

And many more. Symptoms only get more and more severe as childhood goes on but luckily we are able to prevent it.


Treatment/Prognosis:

Every state now screens the blood phenylalanine level of all newborns at about 3 days of age. This is just one of many precautions the country is taking with this life threatening disease. The procedure usually goes like this, a few drops of blood are obtained by a small prick on the heel, placed on a card, and then sent for measurement. If the screening test is abnormal, other tests are needed to confirm or exclude PKU. The goal of PKU treatment is to maintain the blood level of phenylalanine between 2 and 10 mg/dl. Some phenylalanine is needed for normal growth. Children with this disease have a very strict diet that they must follow. They are able and directed to eat:

  • Cereals
  • Starches
  • Vegetables


They also are advised to use a milk substitue.





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PKU diet




Incidence/Frequency:
PKU affects affect about one of every 10,000 to 20,000 live births yearly. The incidence in African Americans is a lot less compared to Caucasin. But, the disorders are equally frequent between males and females.



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PKU testing




Work Cited:




Discussion Questions:
  1. Simply put, what is PKU?
  2. What age group does PKU affect?
  3. What kind of testing are they doing to prevent PKU?